"Tube" frames subdivide into simple beam types, such as the AC Cobra, or the Locust. The Locost has a "space" frame, using a 3-D truss instead of a pair of main tubes with some cross-connection and various extensions. The space frame is far lighter for the same stiffness.
Frames are primarily built up for stiffness, not strength. Thus, mild steel is often just as suitable as 4130 aircraft tubing, titanium or aluminum. What it lacks in ultimate strength goes into useful toughness in a crash.
For a great overview of the options, see "Structures" by J.E. Gordon - it is very readable, and not expensive on eBay.

The Following User Says Thank You to Bicycle Bob For This Useful Post:

If a guy would want to construct a tube frame chassis for a road vehicle, where could he get guidance for its design? I've looked on Amazon for books, I've googled, but haven't found much. There's books on suspensions and what not, but nothing really for the actual frame itself. One thing I have uncovered is Finite Element Analysis. I think the AutoCad Pro program can perform FEA. Is this what you need to calculate strength of a particular design? AutoCad Pro is darn expensive, though...

There are some great software for tube bending and design,some are free.I would not try to reinvent the wheel,look at what others do and build off it.I would not use anything less then 1026 DOM or 4130 steel,you can't go wrong with 1 inch or better,using 4130 you can reduce the thickness for weight saving's but 1026 will be more practical.Look to JD squared for some great ,affordable and safe bending tools.Be careful using cheap bender's,I'm thinking about buying the model 32,hydraulic bender,1000 plus dollars and you can make headers,exhaust,chassis,motorcycle frames etc.Excuse my writing,I just like to get to the point.good luck.

If you are going the tube frame route, you might look at composite tubing. There is "Pultruded" fiberglass tubing in many shapes, round, square, I-beam, flat, angle, etc., which can be stronger and lighter than steel or aluminum, plus no exotic welding skills are need to join the tubes.

I just received a quote from a retailer who will sell small quantities of Fiberglass rectangular tubing. 40' of 2" x 4" for $869 including delivery, this is still too much. There is 184' of surplus 2" x 5" in Springfield Missouri for $225 but they will not ship.

I just received a quote from a retailer who will sell small quantities of Fiberglass rectangular tubing. 40' of 2" x 4" for $869 including delivery, this is still too much. There is 184' of surplus 2" x 5" in Springfield Missouri for $225 but they will not ship.

. . . are very critical. With metal tubing, it is a simple exercise of fit and welding or brazing. With brazing, gusset plates may be needed depending on loading.

Designing composite joints is even more complex as it is not a homogeneous structure that is transferring the loads. The joints in your structure could very well be the weak links in your car.